Selective system



March 26, 1935. J. L. WOODWORTH SELECTIVE SYSTEM Filed March 21, 1934InvniBor: John LWOOdV/OEBH,

His Amowneg.

Patented Mar. 26, 1935 PATENT OFFICE SELECTIVE SYSTEM John L. Woodworth,Schenectady, N. Y., assignor to General Electric Company, a corporationof New York Application March 21, 1934, Serial No. 716,609

'lClaims.

My invention relates to selective systems and, while not limitedthereto, it relates more particularly to that type of selective systemin which control operations are selectively effected in response tocurrent impulses of diflerent duration.

One form of selective system to which my invention relates is shown inmy Patent No. 1,816,755 issued July 28, 1931 in which a bimetallic stripis utilized selectively to reciprocate a switch member between twopositions in response to energization thereof for different periods.

One object of my present invention is to provide a selective system ofthis type which is more economical to manufacture and which operateswith the same or greater degree of reliability.

Still another object of my invention is to provide a novel means wherebya. toggle mechanismmay be selectively actuated to either of its twopositions by movement of a thermal element.

The novel features which I believe to be. characteristic of my inventionare set forth with particularity in the appended claims. My inventionitself, however, both as to its organization and method of operationtogether with further objects and advantages thereof may best beunderstood by reference to the following description taken in connectionwith the accompanying drawing in which Figs. 1, 2, and 3 represent oneembodiment of my invention; Fig. 4 represents a modification thereof;Fig. illustrates a detail, and Fig. 6 illustrates an application of theform of the invention shown in Fig. 4.

Referring to Fig. 1 of the drawing I have shown therein a relayembodying my invention which is adapted selectively to control a loaddevice 1, such as a lamp, which is energized from a power line 2 inresponse to carrier currents received thereover. The carrier currentsfrom the power line 2 may be received in any suitable carrier currentreceiver 3, which may, for example, be of the type shown in my abovereferred to patent, whereby a relay 4 is actuated. The contacts of relay4 control the energizing circuit of the actuating element of theselector relay 5 embodying my invention. This actuating elementcomprises a bimetallic strip 6 having a heating winding 'I wound thereonwhereby the strip 6 deflects to the right when the winding '7 isenergized. This strip 6 is securely attached to a support 8 by means ofa bolt 9 extending therethrough and to which is applied the nut 10. Theenergizing circuit of the winding 7 of the thermal strip extends fromone side of the circuit 2 through the contacts of relay 4, winding '7and the bimetallic 6 strip 6 to the bolt 9, and thence through the boltii and conductor 11 to the other side of the power The switch whichcontrols the load 1 comprises a pair of toggle members 12 and 13, whichare pressed by a spring 14 into endwise engagement, the end of themember 13 pivoting loosely in a V-shaped slot 15 in the lower edge ofthe member 12. The left end of the spring 14 is attached to a supportingmember 16, which member is in turn supported from the member 8. Theright end ofthe member 14 fits into a notch cut into the upper edge ofthe pivot member 12 and thus bears down upon this member tending to biasthe toggle formed thereby to either of its two off center positions.

Motion of'the toggle to the left, underinfiuence of the spring 14, isrestricted by engagement of a contact 17 carried by the member 13 withan additional contact 1'1 which is mounted upon the supporting member16. This contact controls the circuit of the load, which circuit may betraced from one side of the power line circuit 2 through the loadfll'tocontact 17*, thence through contact 1'7 and member 13 to the bolt 9 andnut 10 and thence by conductor 11 to the other side of the circuit. Thuswhen the toggle is in its left-hand position the load 1 is energized.Movement of the toggle member to the right or to the open circuitposition of the switch 1'1, 1'1 is limited by resiliency of the member13 which opposes the resiliency of the spring 14.

This toggle formed by members 12 and 13 is arranged to be actuated bythe thermal strip 6. Its actuation to the right is effected by means ofa U-shape member 18, which is best shown in Fig. 5, and which isattached to the upper end of the strip 6. The left arm of this member isarranged, upon movement thereof to the right, to bear against anadjustment screw 19 carried by the member 12. Thus when the bimetallicstrip 6 deflects to the right the left arm of member 18 engages themember 19 carrying the toggle over center into its right-hand position.The bimetallic strip also carries a screw 20, arranged for adjustabilityby means of a lock nut 21, which upon cooling of the bimetallic stripbears against toggle member 12 tending to carry the switch toward theleft and into the position shown in Fig. 1. In this position the switchis restrained from further movement by means of a screw 22, whichprojects through the upper end of the member 12, the right end thereofbearing down on the right arm of the member 18. Thus the position of thetoggle shown in Fig. 1 is the normal open circuit position of theswitch. In this position the toggle members are just to the left of thecenter position so that it is biased toward the left but is restrainedfrom further actuation by the bolt 22 bearing down at its right end uponthe member 18. V

The operation of the switch in response to carrier current impulses ofdifierent duration may now be understood. Let us suppose, for example,that a short impulse of carrier current is received from the power line2. The relay 4 is actuated and the winding 7 energized during the shortinterval of the impulse. The bimetallic strip 6 is thus caused todeflect slightly to the right. In so deflecting the member 18 moves outfrom under the bolt 22 thereby releasing the toggle, which under itsbias moves to the left. After termination of the short impulse relay 4opens and the winding 7 is de-energized. Strip 6 then cools and deflectsback toward the left the right arm of member 18 abutting against the endof bolt 22. This position of the device is more clearly portrayed inFig. 2 where it will be observed that the right arm of member 18 abutsagainst the bolt 22 and that the toggle 12, 13 is in its left-handposition thereby closing the switch 17, 17.

Let us assume now that a carrier impulse of longer duration is received.Member '7 is of course energized as before and causes a largerdeflection of the strip 6 toward the right. The left arm of member 18now abuts against the screw 19. Owing to the tension of the spring 14further movement is temporarily prevented. Upon further heating of thebimetallic strip 6, however, additional stress is developed in it untila point is reached where the toggle 12, 13 is moved to the right witharapid somewhatsnap like action.

Fig. 3 illustrates the switch in this latter position with the strip 6fully deflected to the right and the toggle 12, 13 in its extremeright-hand position.

Upon interruption of the carrier wave impulse the bimetallic strip coolsand deflects back toward the left. The screw 20 soon engages the togglemember 12 carrying it to the left. Its

' movement to the position shown in Fig. 2, however, is prevented byengagement of the end of screw 22 with the upper edge of the right armof member 18 whereby the toggle is restrained in the position shown inFig. 1 andthe contacts 17, 17 are held in their open circuit position.

The screws 19 and 20 are both provided with lock nuts whereby they maybe adjusted and retained in any desired position thereby to determinethe position of the bimetallic strip when the two members, 20 and theleft arm of U shaped member 18, apply force to the member 12. It hasbeen found by positioning the screw 19 fairly-high on the member 12 thatactuation of the toggle is delayed until suflicient force is accumulatedin the spring 6 to produce a very rapid opening of the switch 17, 17

The bimetallic strip 6 is of course affected by ambient temperatures. Tominimize this effect a second bimetallic strip is provided. This bi-.-metallic strip is shown at 6' in Fig. 1 where it is arranged side byside in the same plane with the strip 6, but sufliciently removedtherefrom that it is not materially influenced by heat generated bywinding 7 on strip 6. Strip 6' is designed to deflect equally with thestrip 6 in response to temperature variations but its deflection is inthe opposite direction. Since the two ends of the two strips aresecurely attached on theblock 8 and by the right arm of member 18 oneopposes the other with respect to ambient temperature variations towhich they are both subjected with the result that ambient temperatureeffects are minimized. Strip 6', however, is provided with no heatingwinding and accordingly it is not actuated by operation of the relay 4with the result that in response to received carrier waves thedeflection produced is in the direction of the deflection of member 6,member 6 during this deflection carrying the member 6' with it againstthe restraint of the latter member.

In Fig. 4 I have shown a further embodiment of my invention whichdiffers from the form shown in Fig. l in that the bimetallic strips 6and 6' are arranged in broadside relation rather than in edgewiserelation as in Fig. 1. The two members are spaced apart at their lowerend by a block 23 and at their upper end by collar 24 carried' on screw20 whereby the two members are sufficiently spaced to prevent the member6' from being affected by heat generated in the winding 7.

In the form shown in Fig. 4 the relay is provided with an additionalcontact 25 carried on the end of a spring 26, which is supported fromthe block 8, and contact 17 projects on both sides of member 13 tocooperate with contacts 17 and 25. The spring 26 is so biased that thecontact 25 engages the contact carried by the toggle member 13 when inthe position shown in Fig. 4 or in the right-hand position of the togglewhich is indicated in Fig. 3. When the toggle is actuated to the left,however, contact 25 is disengaged from the contact carried by the togglemember. Thus the switch 17, 17 25 comprises a single pole double throwswitch which in response to a short impulse is actuated to one positionand in response to a long impulse is actuated to the other position.

Fig. 6 illustrates an application of utility of the form of theinvention shown in Fig. 4 and indicates its use in connection with theoff peak control of domestic hot water heaters. In this figure I haveindicated at 27 a hot water heater having a large main heating element28 arranged near the bottom thereof and an additional heating element 29arranged near the top. Ordinarily the water in the heater is heated bythe element 28 and the power consumed therein is measured by watthourmeter 30. This watthour meter has a voltage coil which is connectedacross the power circuit 2 and a current coil which is connected inseries with the heating element 28 and the contacts 17 and 17 of thecontrol apparatus 31 provided in accordance with my invention. Thisapparatus of course includes the carrier current receiver which receivescarrier wave energy from the power line to actuate the single poledouble throw switch 17, 17 25 of the form of my invention as indicatedin Fig. 4. Normally the switch element 17 is at the left so that theheating element 28 is energized. During periods, however, of peakconsumption of electric energy it may be desired by the power company toremove the domestic water heaters from the power line. This is eflectedby transmitting the long impulse which operates the switch member 17 tothe right thereby opening the circuit of the heating element 28.

During this period of peak load the consumer of course utilizes the hotwater which is stored in the water heater. It may occur, however, due tothe limited storage capacity of the water heater, that this water isinsuflicient to supply his needs until the heating unit 28 is againconnected to the power line. The consumer may in that event close theswitch 35 thereby connecting the auxiliary heating unit 29 across thepower line through switch 17, 25 and the current winding of an auxiliarywatthour meter 33, the voltage winding of which is connected across thepower line 2. Thus the customer is supplied with hot water by means ofhis auxiliary heating member 29 but the amount of energy consumed ismeasured upon a second watthour meter thereby enabling the charging of adifferent rate from that charged for energy consumed by the unit 28. Thelatter meter 33 may comprise the meter which supplies the customer'slamp load as is indicated by the lamp 34 Fig. 6.

While I have shown particular embodiments of my invention it will 01course be understood that I do not wish to be limited thereto since difierent modifications in the mechanical arrangement of elements may bemade without departing from the spirit and scope of my invention, and Iintend by the appended claims to cover all such modifications as fallwithin the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In combination, a toggle switch having two positions, a thermalelement, means whereby said toggle switch is operated from one of saidpositions to the other in response to a certain degree of heating ofsaid element and said toggle switch is operated from said other positionto said one position in response to a different degree of heating ofsaid element, and means to apply heat to said thermal element fordifl'erent intervals of time thereby selectively to operate said toggleswitch to said positions.

2. In combination, a pair of members spring pressed into endwiseengagement to form a toggle, restraining means to prevent actuation ofsaid toggle to one position, thermal means to operate said toggle toanother position and means whereby said restraining means is released bysaid thermal means.

3. In combination, a pair of members spring pressed into endwiseengagement to form a toggle, restraining means to prevent actuation ofsaid toggle to one position, thermoelectric means responsive toenergization for a certain interval of time to operate said toggle toanother position, and means including said thermoelectric means torelease said restraining means after en- 'ergization at saidthermoelectric means for a different interval of time.

4. In combination, a bimetallic strip, a toggle comprising a pair ofmembers spring pressed into endwise engagement, means normally encasingsaid bimetallic strip to prevent motion 01 said toggle to one positionand for disengaging said bimetallic strip upon small movement thereof inresponse to heating thereby to release said toggle to fall to said oneposition, and means whereby upon further movement of said bimetallicstrip said toggle is carried to its opposite position.

5. In combination, a thermal element, a toggle mechanism having twopositions, and a mechanical connecting means between said thermalelement and said toggle mechanism whereby upon small movement of saidthermal element from a normal position said toggle mechanism is operatedto one of said positions and upon larger movement of said thermalelement from said normal position said toggle mechanism is operated tothe other of said positions.

8. In combination, a bimetallic strip, a toggle, said toggle beingarranged to reciprocate between two members carried by said bimetallicstrip, whereby upon moving or said bimetallic strip away irom saidtoggle said toggle is actuated from one position by one 0! said membersover center, and when said bimetallic strip moves toward said togglesaid toggle is actuated back toward said one position, and means torestrain said latter movement of said toggle prior to actuation thereofto said one position.

7. A combination 0! a bimetallic strip, a toggle switch comprising apair of toggle members spring pressed into endwise engagement, abimetallic strip ca ying a pair of members between which one of saidtoggle members reciprocates, whereby upon movement of said bimetallicstrip away from said toggle members said toggle members are carried byone of said last pair of members from one position over center, and uponmovement of said bimetallic strip toward said toggle members said togglemembers are actuated toward center by the other of said last pair ofmembers, and a member rigidly attached to said one toggle member andextending at an an gle thereto to engage an edge of said bimetallicstrip thereby to restrain said toggle members from movement to said oneposition.

JOHN L. WOODWORTH.

